Presently a variety of dispenser-launched, spin-armed munitions are available covering all types of tactical requirements, from jungle penetration to impact detonating. However, with present types of spin-imparting vanes it is necessary to eject the munition either at a high velocity or at a very high altitude, to complete the fuze arming. Since target accuracy requires relatively low dispensing altitudes, present munitions of this kind can be used with high speed aircraft only.
An object of the present invention is to provide a dispenser-launched munition having spin-imparting vanes that can be satisfactorily dispensed or launched from low speed aircraft, including helicopters, at altitudes as low as 100 feet.
Another object of the invention is to provide such a munition with a two-stage spin-imparting vane assembly.
In accordance with the invention, a dispenser-launched munition, such as a fuzed explosive bomb or grenade, is provided with a first set of helically-oriented, rigid vanes having an outer envelope diameter substantially equal to that of the munition body to permit insertion of the vanes with the munition body into the launch tube, and a second set of helically-oriented, resilient, flexible vanes attached to, and constituting outward extensions of, the rigid vanes. The outer portions of the flexible vanes are folded inwardly for insertion within the launch tube, and automatically spring outwardly after being launched to greatly increase the total effective vane area exposed to the air stream, and hence, impart a high spin velocity to spin acceleration of the munition.
Preferably, the means for attaching the flexible vanes to the rigid vanes is designed so that the flexible vanes will be ripped off at a desired spin rate, e.g. 10,000 r.p.m., considerably higher than the normal arming region of 2500 to 3500 r.p.m., after which the munition is spun by the rigid vanes only.